8.3 The Echo Area

The echo area is a one line window which appears at the bottom of
the screen. It is used to display informative or error messages, and to
read lines of input from you when that is necessary. Almost all of the
commands available in the echo area are identical to their Emacs
counterparts, so please refer to that documentation for greater depth of
discussion on the concepts of editing a line of text. The following
table briefly lists the commands that are available while input is being
read in the echo area:

C-f (echo-area-forward)

RIGHT (an arrow key)

M-h, vi-like operation

Move forward a character.

C-b (echo-area-backward)

LEFT (an arrow key)

M-l, vi-like operation

Move backward a character.

C-a (echo-area-beg-of-line)

M-0, vi-like operation

Move to the start of the input line.

C-e (echo-area-end-of-line)

M-$, vi-like operation

Move to the end of the input line.

M-f (echo-area-forward-word)

C-RIGHT (DOS/Windows only)

M-w, vi-like operation

Move forward a word.

On DOS/Windows, C-RIGHT moves forward by words.

M-b (echo-area-backward-word)

C-LEFT (DOS/Windows only)

Move backward a word.

On DOS/Windows, C-LEFT moves backward by words.

C-d (echo-area-delete)

M-x, vi-like operation

Delete the character under the cursor.

DEL (echo-area-rubout)

Delete the character behind the cursor.

On some keyboards, this key is designated BS, for
‘Backspace’. Those keyboards will usually bind DEL in the
echo area to echo-area-delete.

C-g (echo-area-abort)

C-u, vi-like operation

Cancel or quit the current operation. If completion is being read, this
command discards the text of the input line which does not match any
completion. If the input line is empty, it aborts the calling function.

RET (echo-area-newline)

Accept (or forces completion of) the current input line.

C-q (echo-area-quoted-insert)

C-v, vi-like operation

Insert the next character verbatim. This is how you can insert control
characters into a search string, for example, or the ‘?’ character
when Info prompts with completion.

printing character (echo-area-insert)

Insert the character. Characters that have their 8th bit set, and not
bound to ‘M-’ commands, are also inserted verbatim; this is useful
for terminals which support Latin scripts.

M-TAB (echo-area-tab-insert)

Shift-TAB (on DOS/Windows only)

Insert a TAB character.

On DOS/Windows only, the Shift-TAB key is an alias for
M-TAB. This key is sometimes called ‘BackTab’.

C-t (echo-area-transpose-chars)

Transpose the characters at the cursor.

The next group of commands deal with killing, and yanking
text. (Sometimes these operations are called cut and
paste, respectively.) For an in-depth discussion, see
Killing and Deleting in the GNU Emacs Manual.

M-d (echo-area-kill-word)

M-X, vi-like operation

Kill the word following the cursor.

M-DEL (echo-area-backward-kill-word)

M-BS

Kill the word preceding the cursor.

On some keyboards, the ‘Backspace’ key is used instead of
DEL, so M-Backspace has the same effect as
M-DEL.

C-k (echo-area-kill-line)

Kill the text from the cursor to the end of the line.

C-x DEL (echo-area-backward-kill-line)

Kill the text from the cursor to the beginning of the line.

C-y (echo-area-yank)

Yank back the contents of the last kill.

M-y (echo-area-yank-pop)

Yank back a previous kill, removing the last yanked text first.

Sometimes when reading input in the echo area, the command that needed
input will only accept one of a list of several choices. The choices
represent the possible completions, and you must respond with one
of them. Since there are a limited number of responses you can make,
Info allows you to abbreviate what you type, only typing as much of the
response as is necessary to uniquely identify it. In addition, you can
request Info to fill in as much of the response as is possible; this
is called completion.

The following commands are available when completing in the echo area:

TAB (echo-area-complete)

SPC

Insert as much of a completion as is possible.

? (echo-area-possible-completions)

Display a window containing a list of the possible completions of what
you have typed so far. For example, if the available choices are:

bar
foliate
food
forget

and you have typed an ‘f’, followed by ‘?’, Info will pop up a
window showing a node called ‘*Completions*’ which lists the
possible completions like this:

3 completions:
foliate food
forget

i.e., all of the choices which begin with ‘f’. Pressing SPC
or TAB would result in ‘fo’ appearing in the echo area, since
all of the choices which begin with ‘f’ continue with ‘o’.
Now, typing ‘l’ followed by ‘TAB’ results in ‘foliate’
appearing in the echo area, since that is the only choice which begins
with ‘fol’.

ESC C-v (echo-area-scroll-completions-window)

Scroll the completions window, if that is visible, or the “other”
window if not.